Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Unaudited Consolidated Statements of Cash Flows [Abstract]
Net cash provided by operating activities	$ 6,398	$ 1,973
Investing activities:
Purchases of available-for-sale investments	(115,947)	(112,301)
Proceeds from sales or maturities of available-for-sale investments	105,282	89,042
Net (purchases) sales of short-term investments	(7,290)	5
Other investing activities	14,357	(1,154)
Net cash used in investing activities	(3,598)	(24,408)
Financing activities:
Dividends paid to shareholders	(4,080)	(3,977)
Net cash used in financing activities	(4,080)	(3,977)
Effect of Foreign exchange rates on cash and cash equivalents	65	419
Decrease in cash and cash equivalents	(1,215)	(25,993)
Cash and cash equivalents at beginning of period	62,976	73,538
Cash and cash equivalents at end of period	$ 61,761	$ 47,545